The present invention relates to an image display technique which separates light from a light source into light rays of colors (R, G, B) and throws them on a display device to form an image.
In conventional image display techniques of this type, R, G, and B light rays thrown on a display device individually are sequentially moved, or scrolled where light from a light source passes through a lens array and is converted into polarized light in a specific state by a polarization converter and then separated into R, G, and B light rays by dichroic mirrors; the optical paths of the R, G, and B light rays are changed by corresponding rotary prisms so that the rays are projected on the surface of a display device such as a liquid crystal panel in different positions and scroll in a prescribed direction on the display device.
In the above prior art, the overall size and cost of an optical system or apparatus tend to be considerable due to the use of plural rotary prisms and the use of many lenses, which means the presence of many light-transmitting parts, is likely to cause light loss and a decline in screen brightness. Besides, the positions of R, G, and B light projection spots on the display device must be adjusted by controlling the rotational position of the above plural rotary prisms. This adjustment work is usually troublesome. In addition, a motor should be installed for each of the rotary prisms, which may increase the noise level.